反应详情

Anhydrous tetrahydrofuran (15 ml) was added to a mixture of 5-hydroxybenzofuran-2-carboxylic acid methyl ester (1.10 g, 5.7 mmol), triphenylphosphine (1.50 g, 5.7 mmol), and 1-(2-hydroxyethyl)-pyrrolidine (0.66 g, 5.7 mmol) under a nitrogen atmosphere. Diisopropyl azodicarboxylate (1.15 ml, 5.8 mmol) was slowly added to the solution at room temperature. After 2 days, the solvent was removed and the residue was dissolved in a 2:1 mixture of Et2O:EtOAc (150 ml). The solution was washed with 1.0M aqueous NaOH. The product was extracted into 1.0 M hydrochloric acid and the combined acid extracts were washed with Et2O. The extracts were cooled and the pH of the extracts was adjusted to pH 12 with 50% aqueous NaOH. The basic solution was extracted with CH2Cl2 and the organic layer was dried over anhydrous MgSO4, and concentrated to give 5-(2-pyrrolidin-1-yl-ethoxy)benzofuran-2-carboxylic acid methyl ester (0.96 g) as an amber colored solid.

1. customthe solvent was removed
2. dissolutionthe residue was dissolved in a 2:1 mixture of Et2O
3. washThe solution was washed with 1.0M aqueous NaOH
4. extractionThe product was extracted into 1.0 M hydrochloric acid
5. washthe combined acid extracts were washed with Et2O
6. temperatureThe extracts were cooled
7. extractionThe basic solution was extracted with CH2Cl2
8. dry with materialthe organic layer was dried over anhydrous MgSO4
9. concentrationconcentrated